Question: $ { {-1} \times \left[\begin{array}{rr}{0} & {0} \\ {-2} & {4}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-1}\times{0} & {-1}\times{0} \\ {-1}\times{-2} & {-1}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {0} \\ {2} & {-4}\end{array}\right]}$